Modelling wood density and modulus of elasticity in white spruce plantations in Eastern Quebec

Forest managers have to take into account multiple objectives such as stand yield, wood quality attributes, ecological constraints and social considerations when making their decisions. The objective of the present study is to build (i) a dynamic modulus of elasticity (MOEdyn) model and (ii) a core wood density (WDcore) model for white spruce plantations in the Bas-Saint-Laurent Region (Quebec, Canada) to quantify their inter- and intra-stand variations in order for managers to better weigh their different options. Using data obtained from 54 sample plots in 31 white spruce plantations from Eastern Quebec, the MOEdyn of 143 trees and the WDcore of 162 trees were analysed. Dendrometric and stand variables were used to build a MOEdyn linear mixed-effect model and a WDcore multiple linear regression model. The MOEdyn model or explained 66.8% of the total variation, 1.1% of which originated from inter-stand variations. MOEdyn was proportional to diameter at breast height (DBH) and non-linearly decreased with tree growth rate. The WDcore model explained 16.0% of the total variation. The intra-stand variations were represented by a negative relationship between WDcore and growth rate. Inter-stand variations were accounted for by site index and altitude. The performance of the MOEdyn model was satisfactory and in accordance with the literature. However, the WDcore model was below standard, mainly as a consequence of unaccounted intra-individual variations. Nonetheless, raw simulations using these models suggest that white spruce wood from plantations may benefit from intensive forest management.